Transmission assembly

ABSTRACT

A transmission assembly for a drive train of a vehicle for connecting a drive motor to a traction drive of the vehicle, includes a main shift transmission with multiple transmission-ratio stages, wherein multiple shift states of the main shift transmission can be connected by a shifting, as required, by means of shift points of one or more transmission-ratio stages, and a planetary gear, wherein the main shift transmission and the planetary gear are drivingly connected or can be connected as required to each other by means of two connection shafts.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 USC §119, this application claims the benefit of andpriority to German patent application no. 102015211809.6, filed on Jun.25, 2015, which is herein incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The disclosure relates to a transmission assembly for a drive train of avehicle for connecting a drive motor to a traction drive of the vehicle.

BACKGROUND

EP 1 367 296 A1 shows such an assembly, which is suitable primarily forthe drive train of a passenger car or a light-duty commercial vehicle.In larger and heavy-duty commercial vehicles, for example, tractors,however, the decisive factor is that transmission assemblies aredesigned such that a large transmission-ratio spread is guaranteedsimultaneously with a low mass inertia to be synchronized. A hightransmission-ratio spread has the result that the lower gears must havea high transmission ratio. In addition, the requirement for a low massinertia to be synchronized means, with respect to the design with aminimum-to-maximum stress ratio, the lowest possible rotational speedsof the rotating components of the transmission assembly. Consequently,there is the problem of providing a transmission assembly that at leastpartially takes these requirements into account.

SUMMARY

The problem is solved by a transmission assembly for a drive train of avehicle for connecting a drive motor with a traction drive of thevehicle, including a main shift transmission with multipletransmission-ratio stages, wherein multiple shift states of the mainshift transmission can be connected by a shifting, as required, by meansof shift points of one or more transmission-ratio stages, and aplanetary gear, wherein the main shift transmission and the planetarygear are drivingly connected or can be connected as required to eachother by means of two connection shafts and wherein, in one or moreshift states of the main shift transmission, a flow of power runs fromthe drive motor in at least one section of the transmission assembly viamultiple branched power paths to the traction drive, wherein, in atleast one shift state, the flow of power runs in at least one of thebranched power paths via at least two shift points.

Through the transmission assembly according to the disclosure, a largetransmission ratio of the lower gears can be realized for simultaneouslynot too large rotational speeds and mass inertias of the rotatingcomponents, so that short shifting times are achieved when changingbetween gears. Furthermore, advantageously, at least two shift pointsare to be provided in the flow of power, because in this way additionalgears or transmission stages can be generated by a winding path of theflow of forces through the transmission assembly. Furthermore, by meansof the second shift point, group gears within a sub-transmission of themain shift transmission can also be generated. Finally, a transmissionwith good efficiency is produced.

In some embodiments, the shift points are constructed aspositive-locking shift points. In this way, good efficiency and low wearare guaranteed. In addition, this assembly is more cost-effective andsmaller and no holding energy is required, that is, energy is requiredonly for shifting and not to hold the engaged state.

According to some embodiments, in one or more of the shift states, theflow of power runs in at least one of the branched power paths from oneof the connection shafts to the other connection shaft. In this way, atleast a so-called winding path gear is provided. In one or more of theseembodiments, the flow of power runs from one of the connection shaftsvia at least one transmission stage to the other connection shaft.

The planetary gear may include four connection interfaces, of which thefirst and the second connection interfaces can each be connected to theoutside by means of a shift point to a connection shaft of thetransmission assembly, and the third connection interface is connectedor can be connected as required to one of the two connection shafts ofthe main shift transmission, and the fourth connection interface isconnected to the other of the two connection shafts of the main shifttransmission. Here, “can be connected to the outside” means that, fromthe viewpoint of the transmission assembly, there is either a connectionto the drive motor or to the downstream traction drive.

In some embodiments, the third connection interface can be connected viaa shift interface to one of the two connection shafts of the main shifttransmission and the fourth connection interface can be connected via ashift point to the other of the two connection shafts of the main shifttransmission. In this way, a transmission is provided that can beshifted under a full load.

In some embodiments, the main shift transmission is constructed as aparallel shift transmission. In one or more of these embodiments, themain shift transmission is designed with a speed-reducer constructionwith two speed-reducer shafts.

BRIEF DESCRIPTION OF THE DRAWINGS

The transmission assembly according to the disclosure is described withreference to the following figures. Shown herein are:

FIG. 1 an agricultural work vehicle with a drive train that includes atransmission assembly according to the disclosure;

FIG. 2 a block diagram of a transmission assembly according to thedisclosure in a first embodiment,

FIG. 3 a block diagram of a transmission assembly according to thedisclosure in a second embodiment,

FIG. 4 a block diagram of a transmission assembly according to thedisclosure in a third embodiment,

FIG. 5 a block diagram of a transmission assembly according to thedisclosure in a fourth embodiment,

FIG. 6 a gearset layout of the first embodiment of the transmissionassembly,

FIG. 7 a shift matrix of the first, second, and third embodiments of thetransmission assembly,

FIG. 8 a shift matrix of the fourth embodiment of the transmissionassembly,

FIG. 9 a flow of power shown in the gearset layout of the firstembodiment of the transmission assembly,

FIG. 10 a flow of power shown in the gearset layout of the firstembodiment of the transmission assembly,

FIG. 11 a block diagram of a transmission assembly according to thedisclosure in a fifth embodiment,

FIG. 12 a gearset layout of the fifth embodiment of the transmissionassembly,

FIG. 13 a shift matrix of the fifth embodiment of the transmissionassembly,

FIG. 14 a flow of power shown in the gearset layout of the fifthembodiment of the transmission assembly, and

FIG. 15 a flow of power shown in the gearset layout of the fifthembodiment of the transmission assembly.

DETAILED DESCRIPTION

FIG. 1 shows a vehicle 10 in the construction of a tractor with a cabin12 and a drive train 20 in one possible design. The drive train 20includes a drive motor 22 that can be constructed as an internalcombustion engine, a transmission assembly 28, and a traction drive 24.The traction drive 24 includes, in turn, an axle transmission 100 and apermanently driven vehicle axle that can be, for example, a rear vehicleaxle 26. In addition, the traction drive 24 can include a front vehicleaxle 14 that is driven as required.

The transmission assembly 28 includes, in one simple construction, aplanetary gear 40 and a main shift transmission 50 that can beconstructed as a parallel shift transmission or double clutchtransmission. Here, from the viewpoint of a flow of power from the drivemotor 22 to the traction drive 24, the planetary gear 40 can be arrangedin front of or behind the main shift transmission 50. Furthermore, thetransmission assembly 28 can include a not-shown reversing transmission,also called a reverse gear unit. An illustration of the output of thefront wheel drive that can be switched on as required was eliminatedfrom the transmission assembly 28.

FIG. 2 shows a block diagram of a transmission assembly 28 according tothe disclosure in a first embodiment. The transmission assembly includesa main shift transmission in the form of a parallel shift transmission50 and a planetary gear 40. The parallel shift transmission 50 can bedesigned, as shown above, with a speed-reducer construction.

The planetary gear 40 has an input shaft 30 driven by the drive motor 22shown in FIG. 1, starting from which a flow of power can be transmitted,as required, to switchable shift elements 42 ₁, 42 ₂, 42 ₃. By means ofthe shift element 42 ₁, the flow of power can be transmitted to adifferential shaft 44—which can be constructed as a planet wheelcarrier—of the planetary gear 40 and a first connection shaft 52 ₁ ofthe main shift transmission 50. By means of the shift element 42 ₂, theflow of power can be transmitted to a sum shaft 46—which can beconstructed as an annulus gear—of the planetary gear 40. By means of theshift element 42 ₃, the flow of power can be transmitted to adifferential shaft 48—which can be constructed as a sun gear—of theplanetary gear 40 and a second connection shaft 52 ₂ of the main shifttransmission 50.

Starting from the first connection shaft 52 ₁, the flow of power can bedistributed via two spur gear stages 60 ₁, 60 ₂ to a shift point 62 ₁,wherein the shift point 62 ₁ can bring, in turn, a speed-reducer shaft64 into a drive connection with the spur gear stages 60 ₁, 60 ₂. Inaddition, starting from the first connection shaft 52 ₁, the flow ofpower can be distributed via an additional two spur gear stages 66 ₁, 66₂ to a shift point 62 ₂, wherein the shift point 62 ₂ can bring, inturn, a speed-reducer shaft 68 into a drive connection with the spurgear stages 66 ₁, 66 ₂.

Furthermore, from the second connection shaft 52 ₂, the flow of powercan be distributed via two spur gear stages 70 ₁, 70 ₂ to a shift point72 ₁, wherein the shift point 72 ₁ can bring, in turn, a speed-reducershaft 68 into a drive connection with the spur gear stages 70 ₁, 70 ₂.In addition, starting from the second connection shaft 52 ₂, the flow ofpower can be distributed via two additional spur gear stages 74 ₁, 74 ₂to a shift point 72 ₂, wherein the shift point 72 ₂ can bring, in turn,a speed-reducer shaft 68 into a drive connection with the spur gearstages 66 ₁, 66 ₂.

Starting from the speed-reducer shaft 64, the flow of power can betransmitted via a shift point 76 either via a double spur gear stage 78or a spur gear stage 80 to an output shaft 82 of the main shifttransmission 50. The double spur gear stage 78 generates a change in thedirection of rotation and is used in connection with thetransmission-ratio stages driven by means of the speed-reducer shaft 64for forming the reverse gears. Starting from the speed-reducer shaft 68,the flow of power can be transmitted via a spur gear stage 84 to theoutput shaft 82 of the main shift transmission 50. From the output shaft82, the flow of power is transmitted via another spur gear stage 86 to adriven shaft 88 and further to the axle transmission 100.

The embodiment of the main shift transmission shown in FIG. 2 has eighttransmission-ratio stages, wherein the even gears 2, 4, 6, 8 receivetheir flow of power via the first connection shaft 52 ₁, and the oddgears 1, 3, 5, 7 receive their flow of power accordingly via the secondconnection shaft 52 ₂. Alternatively, the main shift transmission 50 canalso have a number of transmission-ratio stages that is different fromeight, for example, ten or twelve transmission-ratio stages. An oddtotal number of gears could also be possible.

FIG. 3 shows a block diagram of another construction of the transmissionassembly, wherein only the deviations relative to the construction shownin FIG. 2 are described and the reference symbols are increased by thecount 100. Starting from the input shaft 130, the flow of power istransmitted directly to the sum shaft 146, which can be constructed asan annulus gear. Via the shift element 142 ₁, the flow of power can betransmitted to the differential shaft 144—which can be constructed as aplanet wheel carrier—of the planetary gear 140 and the first connectionshaft 152 ₁ of the main shift transmission 150. Via the shift element142 ₃, the flow of power can be transmitted to the differential shaft148—which can be constructed as a sun gear—of the planetary gear 140 andthe second connection shaft 152 ₂ of the main shift transmission 150.Via the differential shaft 148, the flow of power can be transmitted viathe shift element 142 ₂ to the second connection shaft 152 ₂.

FIG. 4 shows a block diagram of another construction of the transmissionassembly, wherein only the deviations relative to the construction shownin FIG. 3 are described and the reference symbols are increased anothertime by the count 100. The shift point 242 ₁ is arranged predominantlybetween the differential shaft 248 and the differential shaft 244 of theplanetary gear 240.

FIG. 5 shows a block diagram of another construction of the transmissionassembly, wherein only the deviations relative to the construction shownin FIG. 4 are described and the reference symbols are increased anothertime by the count 100. While the shift point 342 ₁ is further arrangedbetween the differential shaft 348 and the differential shaft 344 andthe shift point 342 ₂ is arranged between the differential shaft 348 andthe second connection shaft 352 ₂, the shift point 342 ₃ is herearranged between the differential shaft 344 and the first connectionshaft 352 ₁.

FIG. 6 shows a gearset layout of the construction described inconnection with FIG. 2 for the transmission assembly 28. To be seen isfirst that the shift points 42 ₁, 42 ₂, 42 ₃ can be constructed asmultiple-disk clutches. The multiple-disk clutches 42 ₁, 42 ₂, 42 ₃ havea common outer clutch cage 32. Via the clutch hub 34 ₃ of the shiftpoint 42 ₃, the sun gear 48 of the planetary gear 40 and the secondconnection shaft 52 ₂ of the main shift transmission 50 can be driven.The annulus gear 46 of the planetary gear 40 is driven via the clutchhub 34 ₂ of the shift point 42 ₂. The planet wheel carrier 44 and thefirst connection shaft 52 ₁ of the main shift transmission 50 are drivenvia the clutch hub 34 ₁ of the shift point 42 ₁. The planetary gear 40can be constructed as a double planet transmission with double planetwheels 36. The second connection shaft 52 ₂ can be arranged within thefirst connection shaft 52 ₁. Furthermore, within the connection shafts52 ₁, 52 ₂ there can be a secondary driven shaft 38 driven directly bythe drive motor 22—see FIG. 1—and provided, for example, for driving apower take-off, not shown in more detail, of the vehicle 10. Withrespect to the main shift transmission 50, reference is made to FIG. 2.FIG. 6 further shows that a first driven gear 90 and a second drivengear 92 can be allocated to the driven shaft 88. The first driven gear90 can be part of a front wheel drive that can be engaged as requiredand the second driven gear 92 can be part of a parking lock of thevehicle 10.

FIG. 7 shows a shift matrix of the embodiments of the transmissionassembly described in FIGS. 2 to 4. The shift matrix first numbers, inthe leftmost column, “Gear total,” the gear stages of the transmissionassembly 28, which are formed by the interaction of the respectivetransmission-ratio stage of the planetary gear 40 and the main shifttransmission 50. In the second column from the left, “Transmission-ratiostage in 50,” the shift states of the main shift transmission 50resulting from the transmission-ratio stages are listed. In the nextcolumns to the right, the shift states of the shift points of theplanetary gear 40 and the main shift transmission 50 are indicated. Thelabel “X” means that a flow of power is transmitted, and the label “N”means that no flow of power is transmitted. Furthermore, the numberswith the subscript indexes, e.g. 74 ₂, indicate the spur gear stage ofthe main shift transmission 50, via which the flow of power istransmitted through the corresponding shift point.

In the column “Transmission-ratio stage in 50,” there is a number inevery second row, namely 0 to 8. In the rows between, an “a” isrecorded. While the transmission-ratio stages designated with 0 to 8 areso-called direct gears, which are formed without a transmission ratio inthe planetary gear 40, so-called intermediate gears are designated with“a,” and are formed by the superimposition of a transmission ratio ofthe main shift transmission 50 with a transmission ratio of theplanetary gear 40. The column “Shift points in 40” shows that in eachgear, only one of the three shift points 42 ₁, 42 ₂, 42 ₃ is closed atone time and transmits a flow of power. Furthermore, the column“Transmission-ratio stage in 50” shows that, below thetransmission-ratio stage 1, there is an intermediate gear a and thetransmission-ratio stage 0. These are, starting from thetransmission-ratio stage 1, gears that are engaged one by one.

FIG. 8 shows a shift matrix of the embodiment of the transmissionassembly described in FIG. 5. The sole difference with the shift matrixshown in FIG. 7 consists in that here, two of the shift points 42 ₁, 42₂, 42 ₃ of the planetary gear 40 are closed simultaneously in order totransmit a flow of power. Otherwise, reference is made to thedescription for the shift matrix shown in FIG. 7.

FIG. 9 shows a flow of power drawn in the gearset layout for theembodiments of the transmission assembly described in FIGS. 2 to 4,whose shift matrix is shown in FIG. 7. FIG. 9 shows the gear 2 listed inthe shift matrix in the column “Gear total.” Gear 2 is an intermediategear that produces a transmission ratio both in the planetary gear 40and also in the main shift transmission 50. The flow of power runs,starting from the input shaft 30, via the shift point 42 ₂ into theplanetary gear 40. In the planetary gear 40, the flow of power branchesinto two parallel power paths, wherein a first power path runs via theplanet wheel carrier 44 to the first connection shaft 52 ₁ and a secondpower path runs via the sun gear 48 to the second connection shaft 52 ₂.While the first power path runs from the first connection shaft 52 ₁ viathe spur gear stage 60 ₁, the first speed-reducer shaft 64, and the spurgear stage 70 ₁ to the second connection shaft 52 ₂, the second powerpath 52 ₂ remains on the second connection shaft 52 ₂, in order toreconnect there with the first power path to form one power path. Thisone power path then runs further via the spur gear stage 74 ₂ to thesecond speed-reducer shaft 68, then further via the spur gear stage 84to the output shaft 82. In summary, it can be said that the flow ofpower in the gear 2 of the transmission assembly 28 undergoes both apower branching into multiple power paths, and also a winding throughthe main shift transmission 50. Here, winding should be understood as acourse of the flow of power that runs, starting from one of theconnection shafts, via two spur gear stages to the other connectionshaft.

FIG. 10 shows the gear 10 listed in the shift matrix in the column “Geartotal.” Gear 10 is an intermediate gear that produces a transmissionratio both in the planetary gear 40 and also in the main shifttransmission 50. The flow of power runs, starting from the input shaft30, via the shift point 42 ₂ into the planetary gear 40. In theplanetary gear 40, the flow of power branches into two parallel powerpaths, wherein a first power path runs via the planet wheel carrier 44to the first connection shaft 52 ₁ and a second power path runs via thesun gear 48 to the second connection shaft 52 ₂. From the firstconnection shaft 52 ₁, the flow of power runs via the spur gear stage 66₂ and the shift point 62 ₂ to the speed-reducer shaft 68. From thesecond connection shaft 52 ₂, the flow of power runs via the spur gearstage 70 ₂ and the shift point 72 ₁ to the speed-reducer shaft 64. Fromthe speed-reducer shafts 64, 68, the two power paths run, on one side,via the spur gear stage 80 and, on the other side, via the spur gearstage 84 to the output shaft 82, where the two power paths join to formone flow of power again. In summary, it can be said that the flow ofpower in the gear 10 of the transmission assembly 28 undergoes a powerbranching in the planetary gear 40 and, in this way, multiple powerpaths are produced through the main shift transmission 50.

FIG. 11 shows a block diagram of a transmission assembly 428 accordingto the disclosure in another embodiment, wherein only the deviationsrelative to the constructions shown in FIGS. 2 to 5 are described andthe reference symbols are increased another time by the count 100. Thetransmission assembly 428 shown in FIG. 11 differs from the assembliesshown in FIGS. 2 to 5 by a planetary gear, which includes two planetwheel transmissions 440 ₁, 440 ₂ interlocked with each other. Otherwisethe main shift transmission 450 is not changed. Starting from the inputshaft 430, the sum shaft 446 ₁—which can be constructed as an annulusgear—of the planet wheel transmission 440 ₁ can be driven via the shiftpoint 442 ₁, and the sum shaft 446 ₂—which can be constructed as a sungear—of the planet wheel transmission 440 ₂ can be driven via the shiftpoint 442 ₂. The two planet wheel transmissions 440 ₁, 440 ₂ areconnected to each other such that the first differential shafts 444 ₁,444 ₂—which can be constructed as planet wheel carriers—are eachconnected to each other, and the second differential shafts 448 ₁, 448₂—which can be constructed as sun gears—are each connected to eachother. Starting from the first differential shafts 444 ₁, 444 ₂, a flowof power can be transmitted via the shift point 442 ₃ to the firstconnection shaft 452 ₁. Starting from the second differential shafts 448₁, 448 ₂, a flow of power can be transmitted via another shift point 442₄ to the second connection shaft 452 ₂. In summary, it can be said thatthe embodiment of the transmission assembly 428 described in FIG. 11 ischaracterized by a planetary gear 440 with two planet wheeltransmissions 440 ₁, 440 ₂ and four shift points 442 ₁, 442 ₂, 442 ₃,442 ₄. In a simplified but alternative variant, the third and fourthshift point 442 ₃, 442 ₄ can be eliminated at the cost of load switchingcapability.

FIG. 12 shows a gearset layout of the construction described inconnection with FIG. 11 for the transmission assembly 428. To be seen isinitially that the shift points 42 ₁, 42 ₂, 42 ₃, 43 ₄ can beconstructed as multiple-disk clutches. To be seen is that a compressivespring 443 ₁, 443 ₂ is allocated to each of the two shift points 442 ₁,442 ₂, wherein these springs load the shift points 442 ₁, 442 ₂ into aclosed shift position. This means that the shift points 442 ₁, 442 ₂interrupt a flow of power when actuated, for example, by means ofhydraulic pressure, and otherwise the flow of power is transmitted.

FIG. 13 shows a shift matrix of the embodiment described in FIG. 11 forthe transmission assembly 428. The structural design of the shift matrixin FIG. 13 is to the same as the design of the shift matrixes in FIGS. 7and 8, insofar as reference is made to their description and at thispoint only the differences will be described. The shift matrix in FIG.13 shows a number, namely 0 to 8, in the column “transmission-ratiostage in 50” in every third row. In the rows between, there is an “a” ora “b.” While the transmission-ratio stages designated with 0 to 8 areso-called direct gears that are realized without a transmission ratio inthe planetary gear 40, with “a” and “b” so-called intermediate gears aredesignated that are realized by a superposition of a transmission ratioof the main shift transmission 50 with a transmission ratio of theplanetary gear 40. The column “shift points in 40” shows that, in eachgear, three of the four shift points 42 ₁, 42 ₂, 42 ₃, 42 ₄ are closedat one time and transmit a flow of power. Furthermore, the column“transmission-ratio stage in 50” shows that, below thetransmission-ratio stage 1, an intermediate gear a, an intermediate gearb, and the transmission-ratio stage 0 are arranged. Starting from thetransmission-ratio stage 1, these are gears shifted one by one.

FIG. 14 shows the flow of power of the embodiment described in FIG. 11for the transmission assembly 428, whose shift matrix is shown in FIG.13. FIG. 9 shows the gear 2 listed in the shift matrix in the column“Gear total.” Gear 2 is an intermediate gear that produces atransmission ratio both in the planetary gear 440 and also in the mainshift transmission 450. The flow of power runs starting from the inputshaft 430 via the closed shift point 442 ₁ into the planet wheeltransmission 440 ₁. Because the shift point 442 ₂ is open, no flow ofpower is transmitted through this point into the planet wheeltransmission 440 ₂. In the planet wheel transmission 440 ₁, the flow ofpower branches out, with one power path running via one of the firstdifferential shafts 444 ₁ and another power path running via one of thesecond differential shafts 448 ₁. With respect to the other course ofthe flow of power within the main shift transmission 450 and the joiningof the two power paths, refer to FIG. 9. In summary, it can be said thatthe flow of power in the gear 2 of the transmission assembly 428undergoes both a branching of the power into multiple power paths andalso a winding through the main shift transmission 450.

FIG. 15 shows the gear 14 listed in the shift matrix of FIG. 13 in thecolumn “Gear total.” The gear 14 is an intermediate gear that creates atransmission ratio both in the planetary gear 440 and also in the mainshift transmission 450. In terms of the flow of power within theplanetary gear 440, refer to the description of FIG. 14, and in terms ofthe flow of power within the main shift transmission 450 and the joiningof the two power paths, refer to FIG. 10. In summary, it can be saidthat the flow of power in the gear 14 of the transmission assembly 428undergoes a power branching in the planetary gear 440 and here producesmultiple power paths through the main shift transmission 450.

LIST OF REFERENCE SYMBOLS

-   10 Vehicle-   12 Cabin-   14 Front vehicle axle-   20 Drive train-   22 Drive motor-   24 Traction drive-   26 Rear vehicle axle-   28 Transmission assembly-   30 Input shaft-   32 Clutch cage-   34 Clutch hub-   36 Double planet wheel-   38 Auxiliary driven shaft-   40 Planetary gear-   42 Shift point-   44 Planet wheel carrier-   46 Annulus gear-   48 Sun gear-   50 Main shift transmission-   52 Connection shaft-   60 Spur gear stage-   62 Shift point-   64 Speed-reducer shaft-   66 Spur gear stage-   68 Speed-reducer shaft-   70 Spur gear stage-   72 Shift point-   74 Spur gear stage-   76 Shift point-   78 Spur gear stage-   80 Spur gear stage-   82 Output shaft-   84 Spur gear stage-   86 Spur gear stage-   88 Driven shaft-   90 Driven gearwheel-   92 Driven gearwheel-   100 Axle transmission

1. A transmission assembly for a drive train of a vehicle for connectinga drive motor to a traction drive of the vehicle, comprising: a mainshift transmission with multiple transmission-ratio stages, wherein by ashifting, as required, by means of shift points of one or moretransmission-ratio stages, multiple shift states of the main shifttransmission can be connected, a planetary gear, wherein the main shifttransmission and the planetary gear are drivingly connected to eachother or can be connected as required by means first and secondconnection shafts, wherein, in one or more shift states of the mainshift transmission, a flow of power runs from the drive motor in atleast one section of the transmission assembly by means of multiplebranched power paths to the traction drive, characterized in that, in atleast one shift state, the flow of power runs in at least one of thebranched power paths via at least two shift points.
 2. The transmissionassembly of claim 1, wherein the shift points are constructed aspositive-locking shift points.
 3. The transmission assembly of claim 1,wherein, in one or more shift states, the flow of power runs in at leastone of the branched power paths from one of the first and secondconnection shafts to the other of the first and second connectionshafts.
 4. The transmission assembly of claim 3, wherein the flow ofpower runs from one of the first and second connection shafts via atleast one transmission-ratio stage to the other of the first and secondconnection shafts.
 5. The transmission assembly of claim 1, wherein theplanetary gear comprises four connection interfaces, of which the firstand the second connection interfaces can each be connected to theoutside by means of a shift point to a connection shaft of thetransmission assembly, and the third connection interface is connectedor can be connected as required to one of the first and secondconnection shafts of the main shift transmission, and the fourthconnection interface is connected to the other of the first and secondconnection shafts of the main shift transmission.
 6. The transmissionassembly of claim 5, wherein the third connection interface can beconnected via a shift point to one of the first and second connectionshafts of the main shift transmission, and the fourth connectioninterface can be connected via a shift point to the other of the firstand second connection shafts of the main shift transmission.
 7. Thetransmission assembly of claim 1, wherein the main shift transmission isconstructed as a parallel shift transmission.
 8. The transmissionassembly of claim 7, wherein the main shift transmission is designedwith a speed-reducer construction with two speed-reducer shafts.